The unprecedented COVID-19 pandemic has indelibly impacted routine healthcare provision across the globe. Nevertheless, management of traumatic injuries has remained a priority patient care service of oral and maxillofacial (OMF) practice. This study aimed to explore the pattern and mechanisms of OMF injuries presenting at a major public dental hospital during a COVID-19 lockdown period in Sri Lanka. An enhanced OMF injury surveillance system was established at the National Dental Hospital (Teaching) Sri Lanka (NDHTSL) on 1 March 2020. OMF injury surveillance data from 1 March 2020 to 31 May 2020 were collated from the “enhanced injury surveillance form”. This period overlapped with the strictly imposed island-wide COVID-19 community lockdown. Pre-COVID-19 period (November 2017 to January 2020) OMF injury data were compared with this period. OMF injuries were categorized as hard tissue, extra-oral or intra-oral soft tissue, upper and middle face fractures and mandibular fractures. Data were analyzed with descriptive statistics, Fisher’s exact and Chi-square tests of significance. A total of 361 OMF injuries were identified among 208 patients who were predominantly males (71.6%); mean age was 24.95 ± 2.76 years. Injuries to gingivae and oral mucosa (26.9%) were the leading type, followed by extra-oral soft tissues (22.1%), periodontal injuries (20.7%) and hard tissue injuries (20.2%). Upper face and mandibular fractures accounted for 2.9% and 1.9%, respectively. Most patients sustained their injuries due to falls at their homes and surrounds. This was significantly increased compared to the pre-COVID-19 period (p = 0.0001). The significant increase in OMF injuries associated with falls around the home during the COVID-19 lockdown scenario in Sri Lanka compared to the pre-COVID-19 period may need further investigation in order to understand the how these injuries may be prevented.